Two-Step Culture Efficiently Improving Shoot Regeneration from in Vitro Leaf Explants of Zizyphus spinosus Hu

摘要

A highly efficient two-step culture protocol was developed for adventitious shoot regeneration from in vitro leaf explants of sour jujube (Zizyphus spinosus Hu.). In vitro shoots of sour jujube were selected as materials. Expanding young leaves were selected as explants. The effect of basal medium, thidiazuron concentration and culture protocol on shoot regeneration was examined. Results showed that two-step culture was better than one-step culture. First, leaf explants were cultured on the basal medium supplemented with thidiazuron (TDZ) and indole-3- acetic acid (IAA) for callus induction and adventitious buds initiation under dark culture, and then subcultured on the basal medium supplemented with IAA and gibberellic acid (GA3) for shoot buds elongation. The optimal media for shoot buds formation and elongation were WPM medium containing 0.5 - 1mg l-1 TDZ and 0.1 or 0.5 mg l-1 IAA and WPM medium containing 0.1 mg l-1 IAA and 0.5 mg l-1 GA3 separately. The effect of light on shoot regeneration was also examined. The adventitious buds regeneration was observed when leaf explants were cultured in the light, but in this case, the buds were smaller buds directly formed from leaf explants, and couldn’t further develop and elongate to form shoots. The two-step regeneration protocol may be applicable to the improvement of this crop by genetic engineering in the future.